There's no set type of backlinks that are the "best". You want a backlink profile to have multiple link types. That means you're going to want:
Tier 1 needs have links from real websites with good metrics. Tier 1s should always be your most valued set of links. Guest posts, niche edits, DR40+, and sometimes PBN links.
Tier 2 can be web 2.0s, edu links, social bookmarks, press releases, etc.
Tier 3 can be a little more spammy if you need them to be. Auto approve blogs, wiki links, forum links, etc.