The SunRace freewheels that are all chromed seem better made than the others with mixed cogs in zinc or chrome finish and some in carbon blue/black steel.

I've used a SunRace chromed 7-speed 13-25 for a couple of years and really like it. Behaves well with my Suntour GPX Accushift system, and I've even occasionally tried it on my bikes with Shimano components -- worked well on both.

I'm trying to find the 7-speed 13-28 version of the same all-chromed SunRace but can't find it, although it's listed on the SunRace website. Might be worth checking into. I think they make a 6-speed version too.