All of this is what we have researched

Space gun (personal favourite)

For instance, with a space gun with a vertical "gun barrel" through both the Earth's crust and the troposphere, totalling ~60 km of lengt h (l), and a velocity (v) enough to escape the Earth's gravity (escape velocity, which is 11.2 km/s on Earth), the acceleration (a) would theoretically be more than 1000 m/s. Applies 100Gs

https://en.wikipedia.org/wiki/Space_gun

Ram accelerator

It is a long tube filled with a mixture of combustible gases with a frangible diaphragm at either end to contain the gases. The projectile, which is shaped like a ram jet core, is fired by another means (e.g., a space gun, discussed above) supersonically through the first diaphragm into the end of the tube. It then burns the gases as fuel, accelerating down the tube under jet propulsion. Other physics come into play at higher velocities.

Space elevator

A space elevator is a proposed type of planet-to-space transportation system.[1] The main component would be a cable (also called a tether) anchored to the surface and extending into space. The design would permit vehicles to travel along the cable from a planetary surface, such as the Earth's, directly into space or orbit, without the use of large rockets. An Earth-based space elevator would consist of a cable with one end attached to the surface near the equator and the other end in space beyond geostationary orbit (35,786 km altitude). The competing forces of gravity, which is stronger at the lower end, and the outward/upward centrifugal force, which is stronger at the upper end, would result in the cable being held up, under tension, and stationary over a single position on Earth. With the tether deployed, climbers could repeatedly climb the tether to space by mechanical means, releasing their cargo to orbit. Climbers could also descend the tether to return cargo to the surface from orbit

Balloons - unreliable because it can be

Solid fuel

Pros:

Can fit more into a space, due to the molecules being closer together.

Mostly used for initial boosters due to it not needed to be limited, or controlled.

Cons:

Lower specific impulse than liquid fuel.

Cannot be controlled, once the fuel is ignited it will keep, until the fuel is depleted.

“intolerant to cracks and voids and often require post-processing such as X-ray scans to identify faults”.

Positive feedback loop can lead to catastrophic failure of the entire system, which is usually caused by the case failing or damage to the nozzle system.

Liquid fuel

Pros:

Cheaper than solid, however the overall cost of the rocket is exponentially more and this is not the biggest factor.

No positive feedback loop which can cause damage.

Can be throttled to control speed.

Cons:

Fills up more space than solid fuel

Hybrid fuel

Pros and cons of both depending on where it is used, however due to the feedback loop and intolerance to cracks it has the same cons as solids with even more cost and little pros from the liquid aspects.

Gel fuel

Pros:

The best of both, fills up as little space as solid, but is as malleable and controllable as liquid fuel.

Cons:

Not much has been done in terms of testing, the only paper I was able to find was one by Bryan Palaszewski, https://www.grc.nasa.gov/WWW/Fuels-And-Space-Propellants/GELLED.htm, this could mean it was considered inferior as the paper is over 20 years old.