IMHO, there are two factors that contribute to this situation:

The new aim assists are making AR, scrambler and laser rifle very deadly at medium-long ranges. A heavy caught in the open isn't agile enough to evade their damage now they have built-in tracking computers. I get melted by a laser rifle so quickly that I can't take 2-3 steps before dropping.

Sentinels don't have a weapon to be effective at those ranges. HMG is practically a close quarter weapon. Forge gun can be used effectively, but takes skill to master, and even then is highly situational against infantry. Sentinels require an anti-infantry heavy weapon that is effective at AR, or at least LR ranges. There's supposedly an Amarr heavy pulse laser on the roadmap which should fill that role. Until such weapon is released, sentinels will have this problem.

Some form of resistance.
25% (max level to explosions)
15% (max level to everything else)

Currently, I can get ~ 1000 armor on my suit but it doesn't matter as all I can do is sit on an objective just to get smoked by someone going in solo with a locus grenade and an AR unless I'm using a Boundless.

The heavy should be something that is not invincible, but feared. Sad that someone with a Caldari assault with 500 shields and 300 armor can solo my Prototype sentinel with 500 shields and 930 armor.. I will say the changes to 1.4 have really made being a heavy much more viable.

I'm a full proto heavy and I rarely use my sentinel or commando dropsuits they aren't worth it. Even with the extra hp its still hard to survive. Heavies used to be beastly before uprising and now the only viable option is to use an AR. I used to be able to solo a whole squad that were running straight at me out in the open. It took skills and strategic flanking to take down a heavy but now with a few bunny hops you can run straight at a heavy and solo it with ease. I used to love being a heavy that was actually scary to run into but now we are a slowly dying breed.

Shouldn't your logis be there to support you through engagements?

I know its unrealistic to expect every single player to always have a "boyfriend" (a term for logis a good friend of mine used to use all the time, cracked me up when he said he was gonna **** up that fat boy and his bf) at all times but I've always imagined the role to be extremely effective in conjunction (and it is, I've seen it but only for a split second as the duo cleaned house)

Heavy alone: use cover, prolong engagement, out-DPS their repping capability, dont get shot!
Heavy with his/her boyfriend: ****..,

Today I went 26-4 just by sitting on an objective (first two deaths were from being blown up when I took on a tank)

It's not that hard to be an effective sentinel, especially with the new maps having some better close quarters areas.

It's just that everyone keeps using armor heavies as frontline fighters...
________________________

Because we lost out "type II" shield heavy, we have to make the most use of our armor. Armor is good for soaking up damage, but not regenerating it. So by sticking to a choke point, you can rack up lots of kills just by letting your health come back up over time. Unlike an assault, you can't just regenerate your health quickly after a battle. Long shield delay times, slow health regeneration. Unless you take the time to let it come back, you're too vulnerable with only half of your total HP.

Our high slots are for damage mods since the normal HMG output isn't very effective, so if you want a frontline shield heavy you have to sacrifice your damage, or just use a light weapon. This is where the problem is. Medium and light suits both have choices for either lots of high slots or lots of lows, but heavies have a max of two high slots, and only 1 if you want to take advantage of the sentinel bonuses :/

I don't think we need damage resistance, but at least another racial variant. A caldari or minmatar heavy + commando would be nice.
_____________________

Lastly, everyone keeps trying to compare a heavy to a tank. You have to remember, tanks are vulnerable when alone, but invincible with a team. if you can stick with a group of infantry that will stick by your side, a heavy becomes an unstoppable force. Either way, you still have to use tactics, cover, and stealth to your advantage.

A good heavy knows the enemy too. If you see a lot of quick run and gun players, you know better than to assault the base head on, and rather slowly make your way there letting them run into you.

I was playing earlier and had an awesome match with my heavy against a whole enemy squad (of 4).

There were concentrating on the other guys they could see at the time and I snuck around the side using cover to my advantage, I think came upon each on of them one by one and gunned them down before they noticed me.

It was a great feeling and one of the best examples I could remember of the heavy being used as it should.

a couple of games later I lost about 5/6 suits in a row because I was trying to move between an open part of the map (our CRU) and the enemies base, and I got wrecked by another heavy using an LAV, he'd drive up, jump out of the car, use his advantage to hose me down and by the time I'd turned around, I was dead.

Very frustrating but reinforced to me, the heavies situational prowess.

I find that Heavy players are, for the most part, bad at this game. Heavy players need to understand that playing a Heavy is more than fitting your suit with "insert special snowflake build here" and pointing your HMG at the enemy until they die. Heavies are slow, lumbering, high EHP suits. This does not mean they are meant to sit on a point until someone figures out the best angle and range to kill them from. This does not mean the heavy is to lumber slowly toward their intended target while holding down their fire button of choice. Why exactly do heavy players think proper FPS mechanics are intended for everyone but them?

No, you can't stand up under withering enemy fire. No one can... not even a tank.

No, you can't sit in one place acting like a fortified, HMG wielding pill box.

And no, no amount of proto-rep tools will make up for your inability to avoid damage.

You have to move, albeit more slowly, just like everyone else. You have to consider approach, range, and flanking. You lumbering up to a target is just stupidity. You aren't dying faster or more frequently because of the suit or it's bonuses. You are dying because you failed to do something. You may have failed to find cover. You may have failed to call and LAV to get across that open space. You may have failed to kill the other player before he/she killed you. I don't know exactly how you may manage to fail, but I do know that it was indeed YOU that failed.

You will find that your play style and skill-level will change when you take a little personal responsibility for your own failures. An LAV will save your hide from being roadkilled/picked off in an open field. Flanking will allow you to take on fewer targets at one time. Using cover effectively will reduce the enemy's ability to apply steady damage to you. Using grenades(Read: Cooking) properly will increase your quality of life.

You will still die. You will still be cut down by AR and LR users before you are able to get them in your optimal. A better player will still manage to kill you with an SMG inside your HMG optimal. But, it won't happen as often. And, you won't be posting whine threads in GD as often either.

Could the Heavy use a little love? Sure, but not the kind of love that allows you to be a one man wrecking machine that takes multiple players to down. We aren't super-caps...