qb:
As Michael posted above, depends on your criteria. Both rifles have been endlessly "sporterized" and re-barreled and both rifles have their fans. From a sporterizing perspective, the K-98 is easier to work with however. The Springfield '03-A3's action is extremely hard, and by that I mean that the steel was case hardened to the point where a file won't even scratch the surface. In order to mount a scope on to the rifle, the points where the mounting screws are attached to the action must be annealed in order to soften the surface so that it can be drilled and tapped. If not done correctly, you can soften the metal too much and ruin what was a perfectly good action. If you can find one these days, the Springfield '03-A4 action was manufactured as a sniper version of the A3 and had mounts built as part of the action and I believe that Conetrol made rings and fittings for the A4. Good luck finding one though, they are rarer than hen's teeth.
K-98 actions are still manufactured today by companies like BRNO and are very popular as are original K-98's.
Hope that helps.