Both i say.
WinUAE is nice for quick testing/playing. but its not always 100% accurate compared to a real Amiga. also smooth scrolling is 1 of those things because of 60hz vsync crap etc.
Real Amiga is just, well the real deal. smooth scrolling and it feels just more nostalgic. disadvantage is that you cannot change 1 slider or option when something goes wrong or doesnt work like WinUAE can