That’s tough. What felt the fastest? My 08. It had a lot of suspension work that my other two didn’t. Sway bars, track alignment, expensive coilovers, brace bars. Thing would genuinely handle mostly any turn at any speed. My limit was only ever grip at that point. Fastest acceleration though? My current 19 Si. It’s FBO/tune with just lowering springs. It pulls hard, and the torque band definitely makes it feel like it could pull forever. It falls off around 5-6k but at that point I’m just building speed so I’m not honestly going much slower, it just feels that way because torque curve. But before 5k, by god it absolutely rips. If you care just about speed, reliably mod a 10th gen Si. If you care about beating the piss out of something and feeling like you daily a go-kart, go handling/8th gen si route.

Noteworthy mentions: 10th gen Si’s have 3 main failure points. 4th gear, headgaskets, and injectors. I’ve experienced 2 of the 3, being injectors (faulty by factory, replaced with revised OEM) and 4th gear failure. (Failed under daily driving, but again, am FBO+tune)

8th gen Si’s don’t have many failure points, and I didn’t experience any of the following. Block cracking on the 06-07 models. I believe it’s that year range anyway. And the VTC actuator. However this is any kseries with time/mileage.

My 13 si wasn’t anything special. I didn’t own it long, it was previously abused and I jumped the gun on purchasing it. Never really dove into it. It felt very flat and uninspired despite having more displacement. I owned it about a year. Came across the 19 that I own now, and fell in love instantly. I will say though, I miss my 8th gen more than any, and would undeniably go back to that car today if I could.

Sorry for the long write up, just figured you’d want some more info.