I recently had some money to invest/save, but will need it soon to pay for house improvements. I opened a 123 account last December. Gas, Electricity, water, council tax, TV/phone direct debits all moved to Santander so the cashback pays the monthly fee. Interest paid £39.76 (£9.94 tax deducted at 20%) so I'll have a bit more tax to pay. My current ISA gives 2% tax free. You have to pay in £500 a month, but this can be from another bank account, eg Barclays. Standing orders set up to move it back and forth.
So if you have all your ISA allowance sorted and want easy access and low risk, the Santander 123 seems to be the best on the market. Once they stick their charges up, reduce the interest rate, stop the cashback or whatever, I'll move my money elsewhere. I think ALL banks do this on savings accounts, tempt you in with an attractive bonus interest rate than after 1 year the interest rate plummets. You have to keep on top of it, just like car/bike/house insurance. Also companies like Sky/Virgin who put your fees up each year ahead of inflation hoping you dont notice and stick with them.
For stockmarket shares, I went for 'preferential' shares. These are safer than normal shares if the company go under as they are higher up the pecking order. They are long term investments and give a set return. The difference between buy and sell price is large, so you dont trade these regularly.
I didnt buy these Aviva
8.75% CUM IRR PRF GBP1, but I'm using as example
https://apps.barclaysstockbrokers.co.uk/Pricing/Pricing/Index?stockId=AV.A8.75% GBP1 means they pay 8.75% of the issue price which was £1, so will pay 8.75p per share. These shares are currently on the market at £1.34, thats a return of 6.5% on your £1.34. 10% tax on dividends.
If they dont pay the dividend because of lack of profits, they give you extra shares. I'll be keeping these for 10 years or so I reckon.
Just my opinion and what I've done, not financial advice.