For anyone playing Dota Underlords, it's pretty evident that the meta hinges on just a few compositions. That does get a little stale, but it does also mean that if you're wanting to climb to higher ranks, it's fairly easy not to fail. Here's the best 3 in the current meta. 

6 Knights + Trolls

Pros

• Super easy to play.
• Pretty hard to lose with. 
• Comes online incredibly quickly. 
• Has very few counters (if any).
• Your last pick can pretty much be anything. 

Cons

• Everyone wants Knight units. You'll have to fight for them. 
• Trolls, similarly to Knights, are also sought after. 
• Assassins are probably their weakest.

6 Hunters + 3 Warriors

Pros

• Most of the front-line are meta units, capable of carrying any match.
• Massive, rapid damage.
• Your front-line pretty much gaurentees your backline goes untouched.
• Your 10th unit is totally variable.

Cons

• Most of the units are late tier.
• You'll often lose early game to Assassin compositions. 
• Knights give you a run for your money. 

6 Assassins + 3 Elusive

Pros

• Amazing burst potential.
• One of the few compositions that can handle Knights.
• Can snowball early game if you land lucky with upgrades.
• It's a fun build to run.

Cons

• Easily countered by Knights/Warriors bunkering in a corner.
• You'll go on a losing streak for a long time before your units come online.
• To gain the Elusive bonus, you need a little bit of luck (Treant is popular).
• Can be tough to gain 6 Assassins, especially if fighting for them against someone else.