I got great gains with suspension, but it is tricky to use. Suspension requires daily injections (2x daily is better). Prop should be injected eod (ed is better) so basically suspension is injected twice as often as prop. Suspension injections are pretty universally painful (you are injecting crystals, which are like little shars of broken glass embedded deep in your muscles - ouch!). I have tried some prop that is very painful, but if you use a prop that is not too concentrated it you should get a much easier injection than suspension.
Milligram for milligram, test suspension is the strongest, since 100mg of it is pure testosterone. 100mg of prop is 80mg test and 20mg of ester, so milligram for milligram test suspension is about 25% stronger than test prop.