You can't really generalise about types of tenants. With 4 properties between myself and DP, my best ever tenant is a single man, and his best ever tenants have been a family with two children and also an old lady. MY worst ever nightmare tenant was a single woman on HB that I was persuaded to take on by the letting agent. She screwed the system I'm going to describe below to the max, and by the time she dumped her keys on the letting agent's desk (no doubt moving on to her next LL victim) the flat was trashed and I ended up nearly £3k out of pocket.
Re Housing Benefit. As I said before, if there are special circumstances, for example a history of mental illness, it might be possible for landlord and tenant to ask for it to be paid direct from day 1. However, normally, even if the tenant requests that, most local authorities won't do this.
So here we have a opportunity for the dishonest. Knowing that the landlord can't force the re-routing of the HB until they are 8 weeks in arrears they just pocket that money. Then the landlord can start to get paid direct, but is already dealing with a significant loss of income. They may have a deposit, but often with HB tenants and in areas where it's more difficult to rent property, they may have been persuaded to take a smaller deposit or none at all. Then the tenants move on at the end of the 6 month AST, and repeat the process to pay for their next holiday.
In worst case scenario, the property has also been left in a mess and needing money spent to let it out again. The landlord is on a hiding to nothing because there is no point in pursuing people on benefits for what can be £1,000's owed.
At least if tenants are in employment it might be worth going after them for what they owe. Bearing in mind of course that if they are bad tenants it will be standard practise for them to default on their last month's rent, therefore negating the benefit of taking a deposit. Oh, and of course they might start off employed, then become unemployed and apply for HB, in which case landlord whistle for a month or two and dig into your savings while you wait for HB to be paid...
If this sounds extreme I don't care. A friend of mine who had just two lovely BTL flats went bankrupt, after a string of bad tenants. All came with great references. She was a great landlord who looked after the properties well and this experience destroyed her.
Whatever you do op, take out landlords insurance, and check to make sure that it will cover if you end up with HB tenants. Mine doesn't and I'm looking into that now.
Again I recommend the landlord's forum that I linked to earlier. They tell it like it is, and give good advice. It's an interesting read for anyone by the way, even tenants. Not only does it give useful information for them, but it will also clearly show why some landlords are so wary about who they let into their properties.
Oh, a 6 month AST is often given initially and it gives landlord and tenant a chance to make sure they've made the right decision. The fact is, if you rent someone else owns the property you live in. That has some advantages and some disadvantages. One of the disadvantages is that if they want or need to sell, or want you to move out, it's their property.