OHV is a more compact, typically more robust, lower maintenance system, but does not like revving(more reciprocating masses to control) and having more moving parts, has more drag.
OHC is mechanically simpler, and stands up to high RPM use better, but that long timing belt/chain needs attention a lot more frequently. Furthermore a OHC engine is huge compared to its OHV counterpart.
Its just a matter of what trade off you want to take, GM uses OHV in the Corvette ZR1 and it keeps up with DOHC Ferraris just fine.