The Airbus A350 XWB ( XWB = extra wide body with less new composite materials applied) VS The Boeing B787 Dreamliner (The world's first major airliner to use composite materials as the primary material in the construction of its airframe.)

Heu... Better in term of Time, speed, distance/range or space...?

Airbus A350 Vs. Boeing's 787: The Wide-Body Wars.

A350 vs. Dreamliner: Which Is More Comfortable?

Whatever the final choice is yours...

Or perhaps the all new Boeing B777X would be a better option...

Boeing's New candidate to complete against the A350 XWB

How can I stop ballooning and losing airspeed while landing?

This especially happens when I am the Pilot in Command on a solo flight. I use throttle as much as possible to control my rate of descent while on final with the runway, but as I come over the runway and airspeed begins to bleed off (throttle at idle at this point), I can never bring myself to push the nose down in order to gain the airspeed back and instinctively pull back too early, and I usually balloon and have to add power, but I can still have a pretty hard touchdown. I am flying a Cessna 172 and I usually have 20 degrees of flap extended. Any tips?

At doing what? Carrying 400 people across the Pacific at once, the B747, carrying 250 people from Japan to LAX or from London to Dehli, the B787.

You can't just say what is the better airplane? A C152 is a far better initial trainer than either of these aircraft could ever be, is it a better aircraft? For that job, yes.

A Spitfire IX could turn inside a B747 about 20 times before the B747 could get round once, is it a better airplane? For shooting down Me109s definitely. For carrying passengers, no not so good.

Is your mistress a better cook than your wife? No, that's not what her job is. Same comparison!

Licenses-qualifications of pilots flying passengers or cargo are exactly same -
There is nothing on a license that restricts a pilot to people or freight only -
A type rating 747 does not say passenger or cargo -

The training is absolutely similar -
Maybe passenger pilots review passenger emergency evacuation procedures -
Security procedures - hijacking/terrorism...
Cargo pilots review expanded mass and balance of payload (being more critical) -

Actually - ground school of cargo pilots is 2 or 3 days longer -
Transport of dangerous goods - incompatible types of cargo - live animals -

In 747 cargo airplane, miscalculation of mass and balance could cause a crash -
Very unlikely with load of passengers, even if moving all passengers in cabin -

With Pan Am (I was pilot 707-727-747) I flew passengers AND/OR cargo flights -
I could be assigned to either one type of flights -
Most pilots liked cargo flights better - "No passenger problems and delays" -

You are probably on the cusp of getting to old for the majors if you have no flying experience at 29.

Essentially you will need to get from a student licence to a level of experience of interest to an airline, in about 6 years. That is a hard ask.

However, the licence level for British airlines is a Commercial and Multi Instrument Rating and that is easily do-able in that time frame. Whether it gets you a job or not is a moot point, with someone like Ezy-Jet, just maybe.

Generally, a major will want you to have considerable jet experience and licences commensurate with that. What you have to remember is that an airline will look for return on investment, so once you get to 40, there are plenty of people in the queue with you who are younger and offer better return for money spent on training them.

If you want to do it, start now.