the performance difference in with the 2.5 VS 2.8 is about 1 second, due to the latter's larger torque output.
Im going to say #1 or #4. If insurance cost is a problem, or you prefer good gas mileage, or you plan on keeping the car a long time or heavily modifing the engine, #1 would be great.
If you want a lot power without mods and dont plan on upgrading the engine much and you can afford to pay more on the insurance, then #4 is an excellent buy.
The letters and numbers go like this:
first number is series
gennerall, the last two are the engine size, so a 318 is a 3 series with a 1.8 and a 328 is a 3 series with a 2.8. However, it is sometimes rounded or left the same due to the name already in place (96+ .18s are really 1.9s)
The letters get a bit more complicated. For the e36, I means fuel injected (FI), IS is FI coupe, IT is FI hatchback, IC is FI cabrio, IX is FI AWD, and TDS is turbo deisel. Other variants include E (economy), CIC (manual FI convertable), IL (FI long wheelbase), but none of these include the e36.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>