Looking for world map making recommendation

I'm finalizing my next campaign, and am looking around for an online tool to create a world map. I really just need to make one map (maybe two), so I'd prefer free to use or a small fee to get started.

I've googled around and found some options, but haven't found one that does exactly what I need. For example, some of my world map is on a plateau and some is lowlands, but that level of varying terrain elevation seems to be an advanced feature for a lot of programs.

I'm wondering if this community has any favorites to recommend. Thanks in advance!