ULi is quite a new player in the motherboard market but from what I have heard, provides some good performance as well, given that you are not expecting to overlock and so on. Have a read here:http://www.ocworkbench.com/2005/uli/m1695/g1.htm. VIA's chipset is known to perform well but yet again not good for overclocking and such more advanced features. I would still chose the VIA mobo over the ULI chipset based mobo, primarily based on support and drivers, which I believe could not be so good with ULi, yet I may be wrong.
In that case, neither is a wise choice. I would go for an Nforce4 Ultra based board in order to overclock well. Some of the best boards for that matter would be DFI, Asus, Abit and Epox....with DFI leading the pack in my opinion.