[Closed] Seatpack or handlebar Harness and drybag?

Whichever you choose, bear in mind whether you will be removing items (i.e. down jacket) mid-ride, and therefore changing the volume requirements of the bag.
If using a seatpack, and the remainder of the contents are too small to sensibly re-size the bag, then the usability will be compromised.

An old school style saddlebag like a Carradice might be better? I don't like carrying too much stuff / weight up front as it upsets handling - OK for clothing / daily food rations. Likewise, many modern soft seat packs are rubbish - slide down, waggle about, don't stay put and not vey good for 'hard' things like stoves

For 5l I'd go seatpack rather than faff around with bars, straps, controls cables and hoses. Might depend on whether you have a dropper though.

Good point about the seatbag stability when not full, I think the handlebar harness and drybag might be more practical, easily removed from harness mid ride for a brew etc.

There are seatpack harness/bag solutions too.

Something like the Alpkit Fuel Pod mounted inside the frame can hold your tools and spares.

What "brew kit" and what duvet? There's a big variance in size/volume of both. A titanium mug with alcohol stove inside is much smaller than something like the jetboil. Similarly a full weight winter duvet with low fill power down is much bigger than a summer weight jacket.

I’ve an evernew titanium pasta pot, spork and a Soto has stove and canister. I have a down jacket which compresses well then just basic tools and two tubes.

Half frame bag e.g. Alpkit Possum, with a small under-the-seatpack for anything you can't get in it.

Why not a backpack?

It’s for my gravel bike while out on all day rides so don’t fancy riding on and off road with a backpack

Alpkit Stem Cell is good for stuff you want quick access to. Handy for food.

PlanetX have some good deala. Just bought some Banjo Brothers kit.

Have opted for a handlebar harness and drybag, this gives me more options relating to the items I can carry and also if it presents itself gives me the opportunity to use for an overnighter.

Cheers all for the input.

Bumbag.

I find a frame bag or half frame bag ideal for that sort of ride (I have a large Blackburn Outpost which zips down into a half frame bag for smaller loads). Stuff's easily accessible - just opening a zip rather than unstrapping a drybag, unrolling, repacking, adjusting straps. The weight's central, and there's probably minimal aero impact if that's a concern.

I prefer to ride with no bags on my person, at thenorthwind I’m not sure a frame bag would take my evernew pasta pot

One could make the case that if you can't fit the pot into a large frame bag, then it (the pot) is too big for a dayride, unless you're brewing up big mugs for 2+ people. I'd be looking at that, rather than trying to fit the bag round the pot.

An Alpkit Mytimug 650 is 103mm in diameter and is a squeeze to fit in to a Wildcat Ocelot framebag, so much so that I've strained the zip. The Ocelot is one of the wider frame bags as well. The Evernew pasta pot is 111mm in diameter so would be even more of a problem. Something the size of a Mytimug 400 is more than big enough for a brew.

...to carry brew kit, down jacket, food and tubes and tool roll...

I'd consider splitting it between two smaller bags, stuff you're likely to want to stop and pull out (snacks/brew kit/jacket) could stuff into a stem cell (or similar) up front where it's easily accessible, the other bits should probably go quite neatly in a conventional seat pack as (hopefully) you won't need to touch those for the whole of a typical ride... That lot can also be transfered quite easily to another bike should you need to...

Good option cookeaa a stem cell for the brewkit and my new Ocelot Fran bag for the other stuff

Cheers

Too late now I guess but for Audax/long day rides I use a bridge Street saddlebag. Much more convenient than a bike-packing seat pack and easily removed to take into a cafe and so on.