Fitted 5 in the last 12 months.
1 x Telford Tempest
Pros: cheap, good customer service from Telford, manufactured in UK, looks decent.
Cons: Awful flimsy cylinder stat that loosely fits into the pocket, easilly gets damaged and 10-15 degrees different to the hot water than comes out the tap, so they have to be set at around 45 or they'll get scolding hot water.
Doesn't come with drain off or female iron to copper fittings. Have to screw the immersions in yourself too which the seals arn't great and cap off the secondary return.
1 x Telford Tornado
Pros: As above but with expansion vessel screwed into top and hidden in case which saves space and looks tidier.
Cons: As above.
1 x Megaflo.
Pros: Everything! The best performance, quality and efficiency in my opinion, hot water was almost bouncing out of the bath and way more powerful than the cold, their integral air gap seems to boost the flow more. Their stats say it all, capable of the highest flow rates of any unvented cylinders I have seen.
Also comes on feet, immersion heaters and cylinder stats fully enclosed so highly efficient and looks the part, comes with all the connections and a drain off too.
Cons: Price, only for those who want the best and willing to pay for it. Size, like with all clyinders with built in vessels or air gaps this takes up height and hot water capacity, they are also slightly wider than most too with no slim models available.
1 x Oso Super S
Pros: looks phenomenal! Very neat pipework too as all connections point out to the back, 2 small expansions vessels fit into the lid, immersions and cylinder stat enclosed in the case.
Cons: Only the price, which isn't as much as a Megaflo.
1 x Center Store
Pros: Price! The cheapest I have found and far superior quality to the Telfords, comes on feet and with immersions and cylinder stat ready fitted and enclosed like the more expensive branded cylinders.
Cons: Looks! Next time I do one I am seriously having another sticker made with my own logo on it to go over the silly looking Center Store one. Also the threads are not good for the 22mm nut and olives that they come with and were difficult to start, even says in the instructions that female iron fittings with ptfe would be better.
Conclusion:
If money no object then I'd go for Megaflo.
If you want the neatest installation I'd go with Oso.
If you want the best Value I'd go for a Center Store if you can bare the cheap looks.
I don't think I'll quote for a Telford again, I may try a Gledhill or Albion next time I want a mid priced one, the look of the Center store is hard to swallow, infact you could go for a Santon which are the same but don't look much better for the extra cost.