Based on my experience with my RS-3, I'd recommend RS-4 easily unless you're after wet weather grip more than dry. I'm eyeing RS-4s next year after clutch change.
The RS-3 were excellent in the wet for the tread pattern, surprised me with the amount of water it can displace. Oh and my friend who daily'd an MY05 STi changed to AD08R and said they were great in the wet, better than OEM RE760 or whatever, but don't last long for obvious reasons.
So it really depends on the OP's needs. How much driving (km's), how much of that in wet (not that much IMO).
The best "street" tyre (UHP) I've driven on were RE050, Advan V105 and FK452.
I wouldn't run RS4 or AD08 unless you're tracking the car. Take a step down to 'ultra high performance' tyres like RE050, S001, Advan Sport V105, Pilot Sport 4, Eagle F1, DZ102, FK453, and my favourite, Ventus K120.
1. Buy shitty ebay ones
2. Retrofit projectors with decent set of RHD ones (for example)
3. Use OE ballast with new D2S bulb
4. Profit a.k.a. enjoy better lighting
The belt deteriorates with age as well, so how long has it been since it was changed? You can have a look at the belt teeth and try to judge the condition.