Here is my read on the equipment being sent, just going off of what I have seen of how Ukraine is fighting, Russia is fighting (TLDR: reports of their good shit like T-90's is few and far between, T-90's have underwhelmed when they did show up, most fighting being done with old T-80's and T-72s that will be eaten alive by most of the gear being sent), and the actual gear at each step:

Germany+Poland and several other NATO nations, Leopard 2, models A4-A6: On paper, these are entirely capable tanks that will get the job done just fine. In practice, Germany was so hesitant to send them because they have had difficulty replacing losses and even maintaining the ones that exist. Because the dirty little secret the German arms industry is not what it once was, and the parts that work well arent German anymore (for instance, H&K is mostly based out of Georgia, USA these days). So they were afraid that once people started sending their Leopards, they would get backfilled by American Abrams and their market share would never recover. The tanks themselves are fine though, and I foresee the Poles putting in great effort to help with them purely on the usual Polish basis of "Fuck Russia."

United Kingdom, Challenger 2: Probably the best option of the traditional tanks being sent their way. It is fairly straightforward maintenance-wise as well as being tough bastards, and their main weakness in NATO formations (not being compatible with all NATO ammo due to the rifled gun) is not exactly an issue for the Ukrainians.

United States, M1 Abrams+M2 Bradley: The Abrams is absolutely a capable tank, and the fuel issues are generally overhyped compared to its actual consumption. The main downside is maintenance, because while an Abrams is generally one of the more reliable tanks out there (as is usual with turbines), it is the most maintenance intensive when it does suffer a breakdown, usually with the entire powerpack having to be removed.

However, the M2 is probably one of the best vehicles the Ukrainians could have asked for for how they have been fighting the war. It will allow them to give a good force multiplier to their infantry (which has proven superior to Russian infantry thus far in the war. It has also had a battle-earned reputation of punching far above its weight, and is can also excel in a heavy scout/heavy cavalry role, which has been the bread and butter of Ukrainian tactics in the war thus far. If its not the best vehicle for their needs being sent, it is second best only to...

France, AMX-10RC: The French were getting clowned on on the military memes boards for deciding this would be the tank they would be sending. But you know what? With how Ukraine has been fighting, this is probably their best option. Ukrainian tanks have largely been characterized by being opportunity hunters not getting directly involved in the, but Ukrainian light vehicle forces have been characterized by being possessed by the cavalry spirit. Wherein they somehow obtained IRL plot armor, and proceed to do utterly retarded bullshit like charge across open fields directly into enemy fire, and somehow not die. So now you want to give them a vehicle that has similar offroad speeds to a Humvee, AND has armor plate that can stand up to medium-caliber autocannons, AND has a 105mm gun? I can foresee them doing some goofy shit with this thing.