Out of all of them, the T34 is the best Tier 8 Premium that I own that you can still buy. It's a tier 8 version of the T29 really. (Sorry but the Type 59 is better...

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The T34-3 is good, but only in an experienced player's hands, don't expect it will be easy to play. The Lowe is similar to the T34, with slightly better hull armour and a comparable gun (less damage and penetration, but better accuracy). Can't commnent on the JT 8.8, but from playing the tier 9 JT, it's very good armour, but a tad slow. The gun looks pretty good on the 8.8 (it's amazing on the "real" JT).
Hope this helps.