I'd personally choose either a V7 or a V9/10 due to the decent performance from both systems and and ease of modding. I owned both a V7 and for a short time a V9 before selling on before it became worthless due to the new consoles coming about on the market. However, if you plan on getting a V9/10 (original PS2 console with the IR Port built in, make sure whoever mods it does the Romeo mod on the LA6508 chip on the motherboard. If you're unsure as to what this is, try Google, the Search button on the forum or the Ultimate Info Sticky at the top of this forum
Infinity is the best chip due to the combination of price, features and user base - so support is never far away if needed.
Any more questions mate, please ask...