At some point you’re likely to want to pick up a second razor, either for a perceived need (like traveling), for giving yourself an even better shave, or simply for the pure joy of it. While recommending a second razor is even harder than recommending the first, here goes:
A slant bar is a good second razor if your goal is to improve your shave or experiment. The Merkur  39C  was my second razor, and one I can heartily recommend. The Merkur 37C has the same head, but with a short handle for those who prefer that.
A travel razor like the Merkur  985CL or 933CL is always a good option if you need or want a highly portable piece of kit. They break down into a tiny pouch about 4cm square, and are just as good as a normal razor when assembled. They are however quite lightweight wth short handles, so they do require a slight adjustment in technique. As an aside; if you want something even lighter – ie; you’re traveling somewhere where a few grams of weight is make-or-break – you can leave one section of the handle at home. Mind you, I have not tried to shave with a razor that has a one inch handle…
Other than that, experiment. If your first razor was a cheap one, you might want to treat yourself to a more expensive piece of modern craftsmanship. If your first razor was a closed comb, try an open comb as the second – or vice versa. Try an adjustable razor, or get a true cheapo from a no-brand manufacturer and try that. Hit the flea markets and eBay and try out some real vintage razors. Not even your imagination is the limit when it comes to options.