I was in this issue about two months ago, when I wanted to get back to life a Pentium 4. I first tried with vector linux (SOHO version). It worked well, but I didn like it. Visually it was pretty ugly.
Then I had found that Lubuntu was THE option for my pentium. Installed the 17.04 version, but it never worked well. It only booted in safe mode, continuing normal booting after (never understood what the problem was). So, I tried Bodhi, and here I am. It works well and showed no problems. Nice option until now.