Any attempt to summarize a sub-style is bound to mislead. At the end, each teacher and dojo have their own style and emphasis. which may itself change over time.
Very true. For example, there are two Tomiki groups in my area, one that does not have any competition and one that does. There is no perfectly valid way to describe the influence and heritage of a life's work to develop a style in one sentence.
Calling Tissier Vanilla...Aikikai is it's own Baskin-Robbins, and not a flavor or style. Tissier has done something special with Yamaguchi's influence that is not the same as many other Aikikai groups. While Aikikai is considered separate from Ki Aikido many Aikikai shihan locally started with Tohei; a number did not.
Go with whoever is available first. I really enjoyed my brief Yoshinkan experience but I lived over a thousand miles away from the dojo I visited. I enjoyed training under teachers who are dead, so there is no practicing with them.
If the best case scenario happens and you find the style a great fit, you'll spend many years with the same people. Pick someone you don't regret spending time with.
Some teachers do not allow students to go to other schools even if they could be complimentary.