after owning both mate the manual was so much more fun, the auto was fine most of the time although it did tend to shift up or down right when i didnt want it to but the rush you get from a full boost kickdown was addictive, and a lot easier to live with in stop start traffic! manuals sound a lot better too, the auto's tend to drone... i bought my auto because it was the only bayside blue one to come up for long time and that was the colour i wanted for my next TT after owning a red manual and selling it to a mate then regretting it straight away! Never got round to the conversion before a little one was on the way and i had to get some money together to fund a few home improvements... bye bye zed.
Personally if i was going to buy another, and im thinking of doing it for next spring, i would 100 percent take the time to find a manual, or budget for a manual conversion if a completed auto project came up.
Best thing is to try both out for yourself if you can, it's all down to personal preference.
Performance differences are all relative anyway, as by now all engines will be giving out different power outputs from standard anyway, be that more or less regardless of transmission