I'm going to go with Tyranitar. Unless you're using it on a dedicated Sandstorm team, there really wasn't a point because Sand Stream was too detrimental to the rest of your team. It has pretty bad synergy with every non-rock/steel/ground not named Cacturne (Sand Stream, not T-tar). It's not so much that T-tar is a bad poke, it's just that Metagross could do basically the same things T-tar could, but had better defensive typing, a solid priority move, and a much, much better ability.
I find two parts of your argument not worthy of an argument.
Firstly:
"It has pretty bad synergy with every non-rock/steel/ground not named Cacturne"
I beg to differ on that. I've found that one of his best partners are bulky grass types, especially Celebi. Despite sharing a common Bug weakness, Celebi can take advantage of the sand to stall out Pokes with its natural bulk, as well as spread paralysis to help out TTar.
Poison Heal Breloom screams to be teamed with TTar too, in my opinion.
Electric types are handy too, notably Zapdos. Zapdos resists quite a few of TTar's weaknesses, and is able to take out waters with its STAB Thunderbolt.
And TTar can pick off some frail Pokes to open up a sweep for one of your Pokes. Gengar, Azelf, Starmie, and the likes can be taken down with Choice Scarf Pursuit/Crunch. Infernape loves for these Pokes to be gone.
Secondly:
" It's not so much that T-tar is a bad poke, it's just that Metagross could do basically the same things T-tar could, but had better defensive typing, a solid priority move, and a much, much better ability."
Comparing TTar to Meta is like comparing peanut butter to jelly. Sure, you stick them both in a sandwhich, but they don't taste the same. They both have high attack stats, but that is where their similarities end in my opinion.
Can Meta put up 101HP subs and do a Boah set? I think not. The best part about TTar is its unpredictability. I love using a Boah set because it catches so many people off guard, and Dark Pulses and Flamethrowers/Ice Beams coming from TTar's respectable Sp. Att stat hurt.
Sure, Metagross has the same Sp. Att stat as TTar, and a higher speed stat, but that does not mean he can pull off a mixed attacking set. TTar has the massive movepool to be able to do this not only effectively, but successfully.
How is Clear Body better than Sand Stream? You are protected from random Intimidates? But who brings in a Gyarados against a Metagross who is likely to be packing Thunderpunch for such the occasion? Sand Stream gives TTar an automatic boost to his special defense, and can turn him into a beastly tank. Plus, the extra heal chipping off of Pokes every turn really helps in the long run.