I think it helps for me to first define different reliabilities.
The set of conditions required to win prior to activating your Hermit Druid.
The set of conditions required to win after activating your Hermit Druid.
How well the combination works against opposing graveyard hate.
If we look at the reliability for the concise 5 card strategies:
This requires all 5 cards involved in the combo to be in your graveyard, library, or in play. Additionally, you need 1GB for Hermit Druid+Lingering Souls. Id say thats fairly reliable.
This requires that your opponent cant counterspell your Lingering Souls / Dread Return, or remove your Druid in response to activation (thus reducing your max creature count to 2). This is slightly less reliable as now any interaction your opponent may have means you need one more card in hand to win (counterspells).
This combo doesnt work under any graveyard hate.
Overall Id say this is one of the less reliable ways to win, but at only 5 cards you have more room to make the conditions work.
The Garna combo instead of Angel still has all the same problems for 2 and 3 as the deck still needs to resolve Dread Return. The other two are different though
- All cards in the combo need to be in your library, or hand. Id say this is unreliable, especially in a long game.
The reliability of 2 can be improved via some minor adjustment of cards/strategy with the real key here being resolution of your Dread Return.
- You can add extra conditions to 1. That is, more conditions to combo, such as counterspells in hand, or additional creatures in play. This could also just be having, say, a copy of animate dead in hand, and extra mana.
- You can add additional cards to your combo. Specifically, Cabal Therapy+Narcomoeba + Bridge from Below. This allows you to sweep your opponents hand before Dread Returning.
- A backup plan. A copy of Memory's Journey for instance can help you recover after a failed attempt for one Green mana.
Dread return is always going to have limitations against graveyard hate though.
A Yawgmoth's Will plan, for instance, could avoid Containment Priest, but would be more mana intensive, 2GGB, and requires a draw step.
Stratetically, you can switch up it up and just need a Maniac in play with your Hermit Druid.