If I am starting from scratch what are the advantages and disadvantages of each type of belt setup?

The pros of V belts: readly available pulleys... core engine, JY, Mancini, Bouchillon ect. Readily available accessories... new, used, rebuilt. Easy fix on the road with access to a parts store. Work well. Work at high RPM if crank pulley diameter reduced.

Cons: Pulleys, brackets ect need to come from same engine and year range or they won't line up.

Pros of Serpentine: may require less adjustment. May be better at high RPM. May simplify engine compartment.

Cons: On road repair, cost.

In terms of appearance, I'd say its individual preference... original or updated?

I went with V belts on my 498B with a mix of used and new pulleys and brackets. I used the late 60's/early 70's bracket setup with a some new pulleys and PS brackets from Bouchillon. The late 70's BB setup on my core engine ('78 Cordoba) wasn't really suitable for my application (except alternator bracket). I also used a 6 1/4" March crank pulley. With my faster running hotter cammed engine, accessory speed is roughly the same as stock with a 7 1/4" pulley.

I think alignment is far more critical on serpentine belts