Maybe i'm the only one but judging from the sheer roaming problems that i'm currently having with Virgin, I'd take Vodafone any day(I never had any problems whenever i was with them). Due to my stupidity, i left Vodafone to join Virgin thinking that they were better at their roaming services- boy, was i wrong!
I'm going back to Vodafone as soon as i fly back home next week.
Im with Vodafone only i can use all my allowances (minutes text data (data capped a 1gb a day) using euro traveler for £3 a day thats if i use it if some days i don't use any i simply don't get charged.
Orange is £2 a day but only for text and minutes again only if used.
Three feel at home is still a better deal if you are travelling in one of the countries covered / included.
I am on VM but I used a 3 PAYG sim card with 500MB data bundle which I was able to use in France recently. I agree it's not the best way to have to swap sim card etc but £5 for 500MB against 250MB is better if all you need is data. Hardly needed SMS or calls as with data you can do all these via whatsapp and viber etc.