Totally have to disagree with Cliff, Id say Nusala is easily the worst of the 3, by some distance.
Reason is simple. Now with excilsor and guides etc the time you are doing normal or easy addies is reduced considerably. These are the adventures Nusala excels on. Even then she isnt miles ahead tbh.
Saying Vargus and Anslem are just for end game adventures isnt strictly true but even assuming they are, saving losses on easy basic adventures is not going to save you much, as the rebuild times are very quick for the troop losses your incur.
At the other end of the spectrum, FTs and Alis, which are where you will earn your real xp, Anslem and Vargus blow Nusala out of the water.
As previously mentioned, even an MMA would be better imo, as the increased capacity (with skills) means they become a viable option to speed up adventures like treasure of wisdom or 3rd thief.
When the going gets tough, and it gets tough allot faster now its quicker to level, the truth is most of the time your on an Ali adventure, Nusala will be the worst option available, compared to MG, Vargus, Anslem, MMA or even a skilled vet.
She is very good for events, and very good at basic addies, but its not saving much and her use becomes more peripheral the harder the adventure you do. Your be doing basic addies for a short period of time nowadays.
Id rather start with anslem + get free MMAs. Id never spend gems on MMAs tbh. id buy vets instead for gems. Cheaper and with skills basically a MG. More MGs are what allow you to do harder addies faster imo.
Anslem for me is clearly the most powerful with skills, especially against super tough enemies and long rounds, which is where u will save time for blocks and plenty f troops.....the problem then is deciding how to skill him best for your play style.
The reason Nusala isnt used much is because when the going gets tough, nusala and her troops and hit points get going lol