One of the best modem brands out there for years has been Zoom.
My first 2400 baud modem was Zoom, my 14.4 modem was Zoom, as was my ISA 56K, as is my PCI 56K V.90. (Although I only use it when I'm at home and not on campus).
But seriously, if you get consistent connection rates w/o errors and failed connects, there is no reason to update your modem. Problems like that may not even be with the modem, but with a noisy phone line.