I have just started on the IVA route and await creditors meeting next step.
I did a lot of research beforehand as I needed help and this took me months to take the plunge.
It should be up to you who you choose through review sites and comments on all sites you can find. Don't forget this is your Journey, so you want to feel comfortable.
I chose Melanie Giles in the end and i have to say since first contact in November to actually spekaing to Mel in January, it has been great. I had to provide all my paper work, which is obvious, but they really do work hard and there is not much you have to do whilst it is all in preparation.
I took this decision by all the positive reviews and found this forum and felt at ease to the fact that Mel is always on the forum answering questions and gave me a sense of she will be there if anything did go wrong
Good luck with who you choose...

But I would suggest reading IVA.co.uk reviews and all other websites, and take a look at postings in here, they tend to give you an idea of which companies to avoid and who is helpful.